1. Field of the Invention
The present invention relates to an x-ray tube and in particular to an x-ray tube of the type having a stationary cathode and a rotating anode with a hollow interior in which a heat-absorption member is disposed.
2. Description of the Prior Art
An x-ray tube is known from German OS 34 29 799 having a stationary cathode with a rotating anode mounted on a shaft, the shaft being seated in the x-ray tube housing by bearings. The anode has a hollow interior in which a heat-absorption member is disposed. The heat-absorption member is connected to the housing via the shaft with a center axis of the shaft being coincident with the center axis of the rotating anode. The heat-absorption member has one end face which engages the interior of the rotating anode. This restricts the mounting and bearings structure for the rotating anode, because it requires both bearing for the anode shaft to be disposed on that side of the anode facing away from the heat-absorption member. It is not possible in this known structure to place the bearings on opposite sides of the anode. As a result, the stiffness or stability of this bearing arrangement is a problem.
In this known x-ray tube, the stray heat generated in the anode during the generation of x-radiation is only partly dissipated to the environment by thermal radiation via the housing. A significant portion of the stray heat is transmitted to the heat-absorption member by thermal conduction, and is eliminated from the heat-absorption member by a coolant. This permits the rotating anode to withstand a higher thermal load because a greater quantity of heat per unit of time can be eliminated.
In this known x-ray tube, to achieve the desired heat elimination from the rotating anode onto the heat-absorption member, it is necessary that the interior wall of the rotating anode and the exterior surface of the heat-absorption member be disposed at an optimally small distance from each other. This means that considerable efforts must be exerted in the manufacture of this known x-ray tube to insure that the center axes of the shaft and of the heat-absorption member are exactly aligned with the center axis of the axle which is used to rotate the anode, otherwise there is the risk that the interior wall of the rotating anode will brush against the heat-absorption member.